Winter warming effects on tundra shrub performance are species-specific and dependent on spring conditions

• Published in: Journal of Ecology
• Main Authors: Krab, Eveline J., Roennefarth, Jonas, Becher, Marina, Blume-Werry, Gesche, Keuper, Frida, Klaminder, Jonatan, Kreyling, Juergen, Kobayashi, Makoto, Milbau, Ann, Dorrepaal, Ellen
• Other Authors: Departement of Soil and Environment, Swedish University of Agricultural Sciences (SLU), Umeå University, Universität Greifswald - University of Greifswald, Agroressources et Impacts environnementaux (AgroImpact), Institut National de la Recherche Agronomique (INRA), Hokkaido University Sapporo, Japan, Research Institute for Nature and Forest (INBO), VR 621-2011-5444, Formas 214-2011-788, Wallenberg Academy Fellowship 2012.0152
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2018
• Subjects: Betula nana; cryoturbation; Empetrum nigrum; shrubs; snow cover; snowmelt timing; spring climate; Vaccinium vitis-idaea; winter climate change; plant phenology; [SDV]Life Sciences [q-bio]; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; [SDE]Environmental Sciences; Arctic; Climate change; Tundra
• Online Access: https://hal.inrae.fr/hal-02623639; https://doi.org/10.1111/1365-2745.12872

International audience Climate change-driven increases in winter temperatures positively affect conditions for shrub growth in arctic tundra by decreasing plant frost damage and stimulation of nutrient availability. However, the extent to which shrubs may benefit from these conditions may be strongly dependent on the following spring climate. Species-specific differences in phenology and spring frost sensitivity likely affect shrub growth responses to warming. Additionally, effects of changes in winter and spring climate may differ over small spatial scales, as shrub growth may be dependent on natural variation in snow cover, shrub density and cryoturbation. We investigated the effects of winter warming and altered spring climate on growing-season performance of three common and widespread shrub species in cryoturbated non-sorted circle arctic tundra. By insulating sparsely vegetated non-sorted circles and parts of the surrounding heath with additional snow or gardening fleeces, we created two climate change scenarios: snow addition increased soil temperatures in autumn and winter and delayed snowmelt timing without increasing spring temperatures, whereas fleeces increased soil temperature similarly in autumn and winter, but created warmer spring conditions without altering snowmelt timing. Winter warming affected shrub performance, but the direction and magnitude were species-specific and dependent on spring conditions. Spring warming advanced, and later snowmelt delayed canopy green-up. The fleece treatment did not affect shoot growth and biomass in any shrub species despite decreasing leaf frost damage in Empetrum nigrum. Snow addition decreased frost damage and stimulated growth of Vaccinium vitis-idaea by c. 50%, while decreasing Betula nana growth (p < .1). All of these effects were consistent the mostly barren circles and surrounding heath. Synthesis. In cryoturbated arctic tundra, growth of Vaccinium vitis-idaea may substantially increase when a thicker snow cover delays snowmelt, whereas in longer ...